To GAW: you can’t bring a BT couple (or half BT couple) as proof. I know of such families. It’s a beautiful thing when it works; why should children be deprived of a parent who is a fundamentally decent and loving person? Why should the children be deprived of a chance to grow up with shalom bayis? I could continue.
Comparing a couple who decide to overcome these differences to stay together because they found each other at a different place and want to stay together to a couple that chooses to embark on this experiment, without the same kind of starting out common ground is apples and oranges.